1. Field of the Invention
This invention relates to a pallet supplier installed in various instruments such as the machine tools of automatic working machines, automatic assembling machines, etc. for supplying pallets to the various instruments.
2. Related Background Art
Generally, a pallet supplier for supplying pallets to various instruments such as the machine tools of automatic working machines, automatic assembling machines, etc. is accurately positioned and installed relative to the machine tool of a working machine, an assembling machine or the like and is provided as an installed type to provide the assembly accuracy, for example, by a robot apparatus. Also, as regards the working and assembling processes in a factory, there are cases where the installation locations of working machines, assembling machines, etc. differ due to limitations in the sizes and installation conditions of respective working and assembling facilities, and in such cases, in order to convey articles, i.e., workpieces, the workpieces are contained in a pallet, whereafter the pallet is placed on an unmanned conveyor or a pallet supplier, which is then conveyed by man power.
FIG. 8 of the accompanying drawings is a side view showing an example of the construction of a pallet supplier according to the prior art. In FIG. 8, pallets 101 are placed at an upper position and a lower position in a supplier 122 for supplying and conveying the pallets 101 by elevator means, not shown, and are conveyed.
On the other hand, a robot apparatus 150 having a robot hand 150h mounted thereon is provided on top of an instrument 170 such as a machine tool or an assembling machine, and workpieces contained in the pallets 101 may be moved to a jig pallet 18 for assembly by the robot hand 150h as indicated by an arrow, and a conveyor 120 provided with a stopper 124 for receiving the pallets 101 and a conveyor 119 provided with a stopper 123 for discharging the pallets 101 are provided between the supplier 122 and the instrument 170 in such a manner that portions thereof are carried on a conveyor bed 130. The pallets 101 may be vertically driven by an elevator 125.
As regards the operation of the pallet supplier constructed as described above, the conveying apparatus 122 comprising an unmanned conveyor is moved to a positioning position in a direction perpendicular to the plane of the drawing sheet of FIG. 8, whereafter the lower pallet 101 in the supplier 122 is moved to the location at which the stopper 124 of the conveyor 120 for receiving the pallet 101, and thereafter the stopper 124 is released and the pallet 101 is moved to the location of the elevator 125, whereafter the pallet 101 is elevated to a work position, and workpieces in the pallet 101 are moved to the jig pallet 18 by the robot hand 150h as indicated by the arrow. When the number of the workpieces remaining in the pallet 101 becomes null in this manner, the elevator 125 is lowered to the level of the conveyor 119, and the pallet 101 is moved to a position in which the right end thereof bears against the stopper 123, whereafter the stopper 123 is released and the pallet 101 is moved to the upper position in the supplier 122, thus terminating the work.
Also, a conveying system for conveying a number of products by the use of a tray, which is provided with an elevator for supplying the tray to a product working station and an elevator for discharging the tray and in which these elevators are individually controlled in movement, is disclosed in Japanese Laid-Open Patent Application No. 60-213630.
Further, an apparatus for carrying a tray containing articles therein by a truck and conveying the tray to a working station, which is equipped with means for gripping the tray, means for supporting the tray until the work is completed in the working station, means for receiving from the supporting means the tray on which the work has been completed in a space portion provided within the apparatus body adjacent to a wagon mounting portion and conveying the tray downwardly, and means for returning the downwardly conveyed tray to the wagon and which is designed such that a preparatory tray and a work tray are pre-mounted on said gripping means and said supporting means, respectively, is shown in Japanese Laid-Open Patent Application No. 63-106214.
Furthermore, an apparatus which is provided with a mechanism for transferring a part box containing parts therein to a part supplying station and a discharge mechanism for discharging the part box which has become empty, and whose space is made small by transferring the part box three-dimensionally is disclosed in Japanese Patent Publication No. 62-29335.